This invention pertains to a windshield wiper unit. In most windshield wiper units used in motor vehicles the wiper arm with its fastening part is fastened directly on a wiper shaft which is driven to and fro and extends perpendicularly to the longitudinal direction of the wiper arm. Such a windshield wiper unit is shown, for instance, in DE-OS No. 28 53 948. Forces operating on the wiper arm in the longitudinal direction therefore act perpendicularly on the wiper shaft, so that there is little danger of the wiper arm coming loose from the wiper shaft due to such forces.
To have a large wiping area, especially in the case of single-lever wiper units, some windshield wiper units have been designed in which the wiper arm can be moved back and forth in its longitudinal direction during a wiping cycle. Such a windshield wiper unit is described in DE-PS No. 24 17 128. This unit has a slide which is supported so as to be movable in its longitudinal direction in a housing which is driven to and fro. The slide is displaced by a gear during a wiping cycle. The end section of the slide projects from the housing in every position. Fastened to this end section is a bolt which protrudes from the slide perpendicularly to its longitudinal direction. A wiper arm is jammed on the bolt in a manner similar to that of wiper units in which the wiper arm is fastened directly on the wiper shaft with a fastening part. The longitudinal direction of the wiper arm is in turn perpendicular to the axis of the bolt, so that the forces acting in the longitudinal direction of the wiper arm, which are particularly great when the wiper arm is moved outwards and inwards, can be absorbed in a relatively simple manner. However, because of the projecting bolt and of the wiper arm being situtated alongside the slide, the known unit has a relatively large overall height.